Clinical characteristics and transfusion profile of hospitalized patients in the Covid-19 intensive care unit at a brazilian University Hospital

ORIGINAL ARTICLE

OLIVEIRA, Mário Cézar de ^[1], IDO, Aline Akemi Segatti ^[2], TERRA, Patrícia Oliveira da Cunha ^[3], FRANCALANCI, Elaine Machado ^[4]

OLIVEIRA, Mário Cézar de et al. Clinical characteristics and transfusion profile of hospitalized patients in the Covid-19 intensive care unit at a brazilian University Hospital. Revista Científica Multidisciplinar Núcleo do Conhecimento. Year 10, Ed. 12, Vol. 02, pp. 39-55. December 2025. ISSN:2448-0959. Access link: https://www.nucleodoconhecimento.com.br/health/clinical-characteristics, DOI: 10.32749/nucleodoconhecimento.com.br/health/clinical-characteristics

ABSTRACT

Introduction: COVID-19 caused by SARS-CoV-2 virus appeared in China and spread around the world. The clinical features are mild inflammation, pneumonia and death. Elderly people are among the groups most at risk and male patients tend to have a worse prognosis, requiring hospitalization in the Intensive Care Unit. Studies have shown an association between infection by the SARS-CoV-2 virus and ABO blood system, in which the virus could associate with the carbohydrates and increase its infection rate. Objective: analyze the clinical characteristics of patients hospitalized to the COVID-19 Intensive Care Unit who were served by Transfusion Agency. Methods: This is a retrospective observational study conducted at the Transfusion Agency of the Hospital de Clínicas of Uberlândia. This study included patients with severe COVID-19 admitted to Intensive Care Unit who required blood transfusion from June 2020 to October 2021. Results: 142 patients were attended to Transfusion Agency, 38 patients were discharged from hospital and 104 patients died. The median age was 60 years, 89 patients were male. Eighty-six patients declared white. Blood groups A (40.8%) and O (45.2%), and RhD positive (88.7%) where the most frequent. Laboratory analysis was 203 x 10³/mm³ platelet, 6.9 g/dL hemoglobin, 21.3% hematocrit, 9.3 x 10³/mm³ neutrophil, 833/mm³ lymphocyte, and 10.5 Neutrophil-to-lymphocyte ratio. Diabetes (39.5%), systemic arterial hypertension (63.0%), obesity (25.2%), pulmonary (31.9%) and cardiovascular (21.0%) disease were the most frequent comorbidities. One hundred thirty six patients received blood transfusion and 128 patients received red blood cell. Conclusion: The evaluation of patients admitted to COVID-19 Intensive Care Unit is necessary for better understanding of the pathophysiology disease; in addition, to know the risk factors provides us prevention and treatment strategies for COVID-19 infection.

Keywords: COVID-19. SARS-CoV-2, Erythrocyte Transfusion, ABO blood system, Mortality.

1. INTRODUCTION

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in the city of Wuhan, China, in December 2019 ¹. Due to its rapid transmission, it spread to many countries caused an outbreak of unusual viral pneumonia, the World Health Organization (WHO) declared it as a global pandemic on March 2020 ^2,3. In Brazil, the first case of COVID-19 confirmed by the Ministry of Health was in the city of São Paulo on February 2020. Since, more than 38 million confirmed cases and more than 709 thousand deaths were registered in Brazil ⁴.

Infection with the SARS-CoV-2 virus causes various symptoms, such as fever, dyspnea, olfactory disorders, dysgeusia, nasal obstruction, and rhinorrhea. However, approximately 20% of infected patients develop pneumonia or respiratory failure and progress to death ⁵. Eighty percent of deaths occur in people with some comorbidity. Furthermore, elderly people or males are among the groups at highest risk and tend to have a worse prognosis than women, requiring admission in the Intensive Care Unit ⁶.

SARS-CoV-2 is a pathogenic virus that replicates in epithelial cells of the respiratory and digestive systems that can express carbohydrate antigens related to the ABO blood system. These antigens are present not only on erythrocytes but also on many epithelial cells ⁷. This interaction involves the viral membrane protein spike (S), which is a transmembrane protein and highly glycosylated, with its cellular receptor angiotensin-converting enzyme 2 (ACE2) ⁸. The S protein expresses glycan antigens A and/or B, reflecting the ABO phenotype of the cells where the virus was produced. In an experimental cellular model for SARS, the physical interaction between the S protein carrying A antigens and the cellular receptor ACE2 was inhibited using human polyclonal or mouse monoclonal anti-A antibody ⁹.

Studies have recorded the association between ABO blood system and SARS-CoV-2 ^10-12. The polymorphism of the ABO system was previously shown to influence susceptibility to SARS infection, where individuals in A and O groups had high and low risk for the infection, respectively ¹³. Evaluating the distribution of the ABO blood system among patients infected with SARS-CoV-2 and healthy patients, the authors demonstrated that the proportion of infected individuals belonging to A group was significantly high compared to the healthy control group, while the proportion among individuals in O group was lower ¹⁴.

Many aspects of COVID-19 still need to be clarified. Advances in prevention and treatment depend on a better understanding of clinical and pathophysiological aspects. Therefore, the aim of the present study was to carry out a retrospective analysis of the demographic, epidemiological and clinical characteristics of patients hospitalized to the COVID-19 Intensive Care Unit who were served by Transfusion Agency.

2. METHODOLOGY

2.1 STUDY DESIGN AND PARTICIPANTS

This is a retrospective observational study conducted at the Hematology and Hemotherapy Unit – Transfusion Agency (AGETRA) of the Hospital de Clínicas of the Federal University of Uberlândia (HC-UFU/EBSERH), Minas Gerais, Brazil. This study included patients ≥ 18 years old with severe COVID-19 admitted to Intensive Care Unit (ICU/COVID-19) who required blood transfusion from June 2020 to October 2021.

2.2 DATA COLLECTION

Epidemiological, demographic, clinical and laboratory data were manually abstracted from electronic medical records using a standardized data collection.

2.3 STATISTICAL ANALYSIS

Continuous variables were expressed as means and Standard Deviation (SD) or medians and Interquartile Range (IQR), according to distribution characteristics. Statistical analyses were performed using statistical GraphPad Prism Software, version 8.0 (GraphPad software, Inc., San Diego, CA, USA).

2.4 ETHICS COMMITTEE

The project was approved by Research Ethics Committee of the Federal University of Uberlândia, with protocol number CAAE 67942823.0.0000.5152.

3. RESULTS

During the COVID-19 pandemic, the Transfusion Agency received requests for blood components for 142 patients who were admitted to ICU/COVID-19. Among 142 patients, 38 (26.8%) patients were discharged from hospital and 104 (73.2%) patients died during hospitalization. The median (interquartile range) age hospitalized patients were 60 (IQR 48.0-68.0) years old, being 50 (IQR 41.0-59.0) years old to discharge group and 63 (IQR 51.5-70.5) years old to death groups. Older age patients were more affected by the disease, fifty (35.2%) hospitalized patients were in the 41-60 age group, and fifty-seven (40.1%) hospitalized patients were in the 61-80 age group, being 49 (47.2%) patients died. Interestingly, in the over 80 age group (9,2%) all patients died (Table 1).

Among hospitalized patients, 89 (62.7%) patients were male, with 75 (72.2%) patients died. Eighty-six (60.6%) patients declared white and 63 (60.6%) patients died. Blood groups A (40.8%) and O (45.2%), and RhD positive (88.7%) where the most frequent among hospitalized patients. In death group, there was no difference between the frequencies of blood groups A (43.3%) and O (43.3%) or B (6.7%) and AB (6.7%). The length of stay was 31.5 (IQR 18.0-48.0) days, with a median of 47 (IQR 31.0-58.0) days for discharge and 27 (IQR 16.5-43.5) days for death groups (Table 1).

Table 1: Demographics characteristics

Laboratory analysis of hospitalized patients was platelet count of 203 x 10³/mm³, hemoglobin 6.9 g/dL, hematocrit 21.3% and neutrophil 9.3 x 10³/mm³, however there was no difference between discharge and death groups. The lymphocyte count of hospitalized patients was 833/mm³ (445-1276/mm³), being that the count of death group (760/mm³) was lower when compared to discharge group (1044/mm³). When evaluated at neutrophil-to-lymphocyte ratio the death group presented a larger ratio (12.9) compared to the discharge group (7.7) (Table 2).

Table 2: Laboratorial results

Among the 142 patients included in the study, 119 (83.8%) patients had comorbidity and 87 patients died (85.6%). Furthermore, patients who had several comorbidities (78.1%) were more susceptible to death (81.6%) in comparison with discharge group. Several comorbidities have been linked to a worse prognosis during the COVID-19 pandemic. Among the study groups, the comorbidities that presented the highest frequency were diabetes (39.5%), systemic arterial hypertension (63.0%), obesity (25.2%), pulmonary (31.9%) and cardiovascular (21.0%) disease. All these comorbidities showed differences between the discharge and death groups (Table 3).

Table 3: Health risks

From 142 patients, 136 patients received blood transfusion, therefore 37 (27.2%) patients discharge and 99 (72.8%) death groups. Thirty-eight (27.9%) patients required a transfusion and 98 (72.1%) patients required several transfusion. Among polytransfused patients, 70 (70.7%) patients died. One hundred and twenty-eight (94.1%) patients received red blood cell, three (2.2%) patients received fresh frozen plasma and six (4.4%) patients received platelet transfusion. Ninety-nine patients death group received a blood transfusion, being 97 (98.0%) patients to red blood cell, 1 (1.0%) patient to fresh frozen plasma and 6 (6.0%) patients to platelet (Table 4).

Table 4: Transfusion profile

4. DISCUSSION

COVID-19 is a systemic multiple organ damage disease with the lung as the main target organ. It can cause severe lung injury and SARS in severe cases which may lead to death. The COVID-19 pandemic brought new challenges to humanity in different sectors of society. Efforts have been made to understand the transmission, pathophysiology, transmission, clinical behavior, risk factors and viral susceptibility of people ¹⁵.

Previously, studies have reported that older age is an important predictor of mortality for Middle East Respiratory Syndrome (MERS), SARS and COVID-19 ^16-18. In the study carried out by Dalmazzo and colleagues, the authors evaluated 3014 hospitalized patients diagnosed with COVID-19 and they found that increasing age is associated with death these patients ¹⁹. In our study, we verified this relationship, where older ages had a greater number of patients in the death group. Age-related defects in T and B cell functions and cytokine/chemokine signaling profile are altered to a type 2 cytokine response, moreover, the immune dysregulation is accompanied by a strong procoagulant state can lead to a deficiency in the control of viral replication, leading to worse outcomes ²⁰.

Blood system can play a direct role as receptor, intracellular uptake, signal transduction and adhesion for pathogens infection. ABO blood type has been associated as risk factors from Hepatitis B, Hepatitis C, malaria, Human immunodeficiency virus (HIV), Chikungunya virus, West Nile virus and Helicobacter pylori ^21-23. The pandemic caused by new SARS-CoV-2 triggered research to evaluate the relationship between viral susceptibility to diseases and blood groups type. Zhao and colleagues published results of a comparison between ABO blood group distributions in 1775 patients with COVID-19 and control population of healthy people from Wuhan hospital, and found that blood group A was associated with an increased risk of infection and a higher mortality, whereas blood group O was associated with a decreased risk ¹¹. Li and colleagues published similar results of blood type distribution from three hospitals in Wuhan. They concluded that patients with the A phenotype were at higher risk of hospitalization and develop pneumonia and die, while patients with the O phenotype had lower risk ²⁴. On the other hand, other studies bring divergent results. Abdollahi and colleagues evaluated 397 COVID-19 patients in the Iranian population and described a higher rate of infection in group AB patients and a lower rate in group O patients ²⁵. In a multi-institutional study, 1289 patients tested positive with a known blood type, and the authors did not find any correlation between group A and COVID-19, however group O patients had a lower risk of COVID-19 and B/AB groups patients had a higher risk ²⁶. Our study no identified any differences in mortality that could be attributed to the ABO phenotype.

Studies have also examined the relationship between the Rh(D) phenotypes (positive and negative Rh blood types) and COVID-19 infection. One study performed by Arac and colleagues evaluated a total of 392 patients and showed an association between Rh(D) positive blood groups and COVID-19 pathogenesis as potential risk factors ²⁷. Another study carried out in New York-Presbyterian/ Columbia University Irving Medical Center Hospital in New York City showed that Rh-negative blood type to have a protective effect for infection, intubation and death on COVID-19 ¹². Although studies show this protective association involving negative Rh blood, in our study we did not identify this protective relationship involving the Rh blood group.

Laboratory markers provide important information to understand the diagnosis, prognostication and therapeutic monitoring of the diseases. Studies show that patients with COVID-19 infection hospitalized in ICU have a decrease in hemoglobin and platelet values, lymphopenia and neutrophilia ^28,29. Similar results were found in our study among patients who were admitted to ICU/COVID-19, although there was no difference between the discharge and death groups.

Neutrophil-to-lymphocyte ratio (NLR) are important inflammatory biomarkers for death risk in patients with sepsis, cardiovascular diseases and severe COVID-19 ^30-32. A study carried out by Terra and colleagues found that the NLR ratio of non-survivor group (12.63) was greater compared to survivor group (7.43), furthermore, when combined with D-dimer (≥2µg/ml) are predictor variable of death risk in severe COVID-19 infection ³³. Li and colleagues performed meta-analysis, and concluded that NLR has good predictive values on disease severity, mortality and can help identify potentially severe cases early in COVID-19 infection ³⁴. In our study, death group patients presented a high NLR ratio compared to discharge group, this relationship is a reflection of low lymphocyte count in death group. NLR elevation may be due to dysregulated inflammatory cytokines, increase of neutrophil and regulation in lymphocyte cell death pathway, caused by the mechanism of SARS-CoV2 infection ³⁵.

COVID-19 infection patients associated comorbidities conferred a higher risk of severe COVID-19, ICU admission and overall fatal outcomes. Diabetes, cardiovascular disease, hypertension, renal and pulmonary diseases, are frequently comorbidities that increase the case fatality rate ^36,37. Guan and colleagues reported in a study with 1590 COVID-19 hospitalized patients from China that 25.1% patients had at least one comorbidity, while 8.2% patients had two/more comorbidities, which hypertension, diabetes, cardiovascular diseases and chronic kidney disease were the most common and correlated with poorer clinical outcomes ³⁸. Additionally, studies reported that obese patients had associated increased with more severe disease and worse outcomes in adults hospitalized with SARS-CoV-2 infection ^39,40. We verified a profile of comorbidities similar to the study above, being systemic arterial hypertension, diabetes, obesity, pulmonary and cardiovascular disease the most frequent. In addition, patients who had some comorbidity had poorer clinical outcomes. Therefore, preventive efforts should especially target these high-risk populations with pre-existing comorbidities.

Patients who are admitted to the ICU have higher mortality rates and require larger amounts of blood transfusion. Dalmazzo and colleagues evaluated the transfusion need of 325 patients admitted to the ICU. In total, 3187 blood products were transfused, being 1364 packed Red Blood Cells (RBCs) in 303 patients, 1101 platelet units in 80 patients and 303 Fresh Frozen Plasma (FFP) in 49 patients. Furthermore, the authors identified age, comorbidities, low platelet counts, low hemoglobin levels and admission to ICU as risk factor for transfusion ¹⁹. In our study, due to the low hemoglobin levels of patients hospitalized in the ICU/COVID-19, packed red blood cells were the most used blood components.

In conclusion, this study showed a high mortality rate among patients admitted to the adult ICU/COVID-19. Older and male patients were more affected by SARS-CoV-2 infection. The presence of ABO blood system antigens has not been shown to be directly related to poor prognosis among infected patients. The ratio between neutrophils and lymphocytes proved to be an important tool for monitoring infection, in which patients with low lymphocyte dosages were more susceptible to SARS-CoV-2 infection, and the presence of comorbidities was a risk factor for patients infected with COVID-19. Future studies into the pathophysiology of COVID-19 disease may guide us towards better treatment and understanding the relationship between the ABO blood system and COVID-19 infection.

FUNDING

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors

CONFLICTS OF INTEREST

The authors declare no conflicts of interest to disclose.

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^[1] Advisor. PhD in Applied Immunology and Parasitology, Master’s in Applied Immunology and Parasitology, Bachelor’s degree in Biomedicine. ORCID: https://orcid.org/0000-0002-8690-6000. Currículo Lattes: http://lattes.cnpq.br/8924508898024445.

^[2] Bachelor’s degree in Biomedicine. ORCID: https://orcid.org/0000-0002-3212-4564. Currículo Lattes: http://lattes.cnpq.br/9372019018614359.

^[3] Professional Master’s degree in Hemotherapy and Biotechnology, Bachelor’s degree in Medicine. ORCID: https://orcid.org/0000-0001-5322-6933. Currículo Lattes: http://lattes.cnpq.br/0927575754208692.

^[4] Bachelor’s degree in Biomedicine. ORCID: https://orcid.org/0000-0003-0346-7389. Currículo Lattes: http://lattes.cnpq.br/0959040227747675.

Material received: June 24, 2025.

Peer-approved material: July 23, 2025.

Author-approved edited material: December 13, 2025.